Patent GB-1413345-A (GB)
Title: Apparatus and method for automatic design of split die cavities
IPC: G05B19/4093
Filed: 1973-09-11
Abstract: 1413345 Automatic control DIECOMP Inc 11 Sept 1973 [29 Sept 1972] 42742/73 Heading G3N Relates to the automatic design of split die cavities, being particularly concerned with determining the most suitable locations for split lines which are to radiate outwardly from a proposed die cavity contour whereby the material of the die structure surrounding each cavity and forming its cutting edges, will be divided into segments which can be readily machined by a grinding wheel. Various criteria are taken into account in the determination of split lines location. An axis of symmetry of the contour is preferable if it has a large total length of contour sides parallel to that axis and if the axis does not intersect a concave portion of the contour. Where no symmetry axis exists, splits may originate in any straight side and convex arc, and parallel split lines are desirable. These and other criteria are determined by logic circuits which process information regarding co-ordinates of the contours stored in a store 10, Fig. 1 (not shown), and which may be manually keyed thereto or provided by a drawing co-ordinate digitizing machine, or a die contour may be continuously scanned. Processing a symmetrical contour. Figs. 4 and 5. A control means (14), Fig. 1, (not shown), scans contour information in storage cells (10) and scans information in storage cells (12) describing the symmetry axis. For each axis, signals are directed to appropriate processors which test for intersection of the respective axis with a concave arc of the contour. Next, in Fig. 5 circuit the total length of sides parallel to that axis are determined. To effect this the contour information in cells 10 is scanned and the scanner passes the X, Y co-ordinates signals corresponding to the two ends of each straight side to respective summers 39 and thence to a divider to produce a ratio sum x/sum y signal. This ratio signal is fed to a function generator 41 which produces a signal as a function of the arc tan of its input and significant of the angle of a side to the axis. If a side is parallel thereto a comparator 42 triggers a gate 43 to pass a signal proportional to the side length to a cell 44 where it is added to all previously recorded parallel length values. The length signal is produced by squaring the outputs of summers 39 in multipliers 45 the outputs of which are added at 46 and the square root of the sum is derived in a rooter 47 the output of which is the side length. The nearness of an axis to vertical is also a criterion and the absolute magnitude of the sine of the given axis angle is determined. In Fig. 4, at each step in a scan signals from 32a, 32b which are functions of the determined sine of an axis angle and total parallel length respectively, are given weighting factors by multipliers 33 and are added at 34. At each step in the scan a synchopulse from 34a causes a comparator 35 to compare the resulting sum with the maximum previous value thereof stored in a cell 36. If the current sum is the greater, comparator 35 triggers gates 37 to pass it and an index number given to the split axis to storage cells 36, 38 respectively. At the end of the scan the cell 38 will have the index number of the preferred split axis. The circuits Figs. 4, 5 may likewise be used for non-symmetrical cavity contours. Fig. 6 (not shown) illustrates a circuit for determining whether an axis of symmetry passes through a concave portion. Fig. 8 (not shown) illustrates a circuit for determining the centre of gravity of a contour. Fig. 10 (not shown) is for determining whether an axis of symmetry exists.